Transcoder: Adopt MediaCodec HDR->SDR conversion

Request MediaCodec to convert all HDR content to SDR.
Return an error if the conversion is not supported.

Bug: 178106748
Test: Unit tests
Change-Id: I2fe79170398d46ddc4fa6d4c81472a13046d5f47
diff --git a/media/libmediatranscoding/transcoder/NdkCommon.cpp b/media/libmediatranscoding/transcoder/NdkCommon.cpp
index a7b79dc..f5c9594 100644
--- a/media/libmediatranscoding/transcoder/NdkCommon.cpp
+++ b/media/libmediatranscoding/transcoder/NdkCommon.cpp
@@ -40,6 +40,9 @@
 const char* TBD_AMEDIACODEC_PARAMETER_KEY_VIDEO_BITRATE = "video-bitrate";
 const char* TBD_AMEDIACODEC_PARAMETER_KEY_MAX_B_FRAMES = "max-bframes";
 
+/* TODO(lnilsson): Finalize value or adopt AMediaFormat key once available. */
+const char* TBD_AMEDIACODEC_PARAMETER_KEY_COLOR_TRANSFER_REQUEST = "color-transfer-request";
+
 namespace AMediaFormatUtils {
 
 #define DEFINE_FORMAT_VALUE_COPY_FUNC(_type, _typeName)                                      \